The present invention is directed to medical systems, and more specifically, to systems, apparatus and methods for limiting the re-usage of medical probes, such as catheters and surgical probes.
Catheters, surgical probes and related probe devices (collectively referred to, hereinafter, as xe2x80x9cmedical probesxe2x80x9d or xe2x80x9cprobesxe2x80x9d) are used today in diagnostic and therapeutic medical procedures that require surgical or minimally invasive access to target tissue areas within interior regions of the body. During these procedures, a physician locates the distal end of the medical probe at the target site by, in the case of a catheter, steering the medical probe through a main vein or artery (typically, the femoral vein or artery), or, in the case of a surgical probe, advancing the medical probe through the surgical opening leading to the target site.
The physician then operates the medical probe to activate a functional component mounted at the probe distal end, thereby providing therapeutic treatment to and/or diagnosis of the interior region. Due to the potential of passing any of a variety of dangerous diseases from one patient to another, prudent consideration dictates that the reuse of such probes should be prevented or, at the least, minimized. Typically, medical probes that are re-used are sterilized between uses to kill any disease-causing agents and to remove any tissue that has collected on the medical probe during the previous use. Sterilization of used medical probes, however, is not fool-proof, and oftentimes ineffective when tissue located on the medical probe is not exposed to the full effect of the sterilization process. Thus, even a sterilized medical probe may pose a threat to patients.
Minimizing re-use of medical probes that provide therapy becomes even more critical. During the therapeutic process, it is important for the physician to control the therapeutic component at the probe distal end carefully and precisely, so that adverse damage to a therapeutic component of the medical probe does not occur. Sterilization of and re-use of therapeutic medical probes subjects the therapeutic component to mechanical, chemical and/or thermal stress, thus jeopardizing the control that the physician may have of the therapeutic component.
The need for careful and precise control over a therapeutic medical probe is especially critical during procedures that ablate tissue within the heart. These procedures, called electrophysiological therapy, are becoming more widespread for treating cardiac rhythm disturbances. When inside the desired chamber of the heart, the physician manipulates a steering mechanism to place one or more electrodes located at the distal end of the medical probe into direct contact with the heart tissue to be ablated. The physician then directs radio frequency energy from the electrodes through the tissue to an indifferent electrode, thereby ablating the tissue and forming a lesion. If the electrodes or the electrical wires connected thereto are worn or faulty, however, ablation may be ineffective and, in the worst case, may cause charring of the heart tissue.
Preventing or limiting re-usage of medical probes, while still allowing legitimate use of these probes, is made difficult by a possible scenario wherein the physician uses the medical probe, temporarily disconnects the probe from the control unit, and reconnects the probe to the control unit to continue the procedure. Thus, there is a danger of deeming the continued procedure to be re-usage of the medical probe, which may result in the probe being rendered prematurely inoperable.
Thus, it would be desirable to provide an improved medical system for minimizing the re-usage of medical probes, while still allowing legitimate use of these probes.
The present invention is directed to improved apparatus and methods for obtaining information on and limiting usage of medical probes, such as, e.g., catheters and surgical probes.
In a preferred method performed in accordance with a first aspect of the invention, the usage of a medical probe is monitored by initially operating the medical probe, determining a time when the medical probe is initially operated to obtain an initial probe usage time, and electronically storing the initial probe usage time within the medical probe.
By way of non-limiting example, the initial probe usage time is stored in non-volatile electronic storage componentry for use after a procedure is performed on a patient. For example, the initial probe usage time can be used to limit or prevent the use of the medical probe in subsequent procedures, or to facilitate troubleshooting of the medical probe if defective.
In a preferred method performed in accordance with a further aspect of the invention, the usage of a medical probe having electronically stored therein an initial probe usage time is limited by reading the initial probe usage time from the medical probe, comparing the initial probe usage time with a reference, such as, e.g., the current time, and preventing operation of the medical probe based on the time comparison.
By way of non-limiting example, the medical probe is connectable to a control unit, and the initial probe usage time is subtracted from the reference time to determine an elapsed probe usage time. The elapsed probe usage time can be determined one time per medical probe connection, or alternatively, periodically after a medical probe connection. If the elapsed probe usage time exceeds a predetermined elapsed time limit, operation of the medical probe is prevented or terminated.
In a preferred embodiment constructed in accordance with another aspect of the invention, a control unit, for connection to a medical probe having electronic storage componentry, comprises a clock configured for generating a timing signal and a control circuit electrically coupled to the clock. The control circuit is further configured to electrically couple to the electronic storage componentry for deriving an initial probe usage time from the time signal and writing the initial probe usage time to the electronic storage componentry.
By way of non-limiting example, the control unit is an RF generator with a microprocessor as the control circuit. The microprocessor is configured for writing the initial probe usage time into the electronic storage componentry only if the medical probe is effectively operated. In the case of an ablation medical probe, effective operation contemplates the creation of a tissue lesion.
In another preferred embodiment constructed in accordance with still another aspect of the invention, a control unit, for connection to a medical probe having electronic storage componentry with an initial probe usage time stored therein, comprises a clock configured for generating a timing signal and a control circuit electrically coupled to the clock. The control circuit is configured to electrically couple to the electronic storage componentry for reading the initial probe usage time stored in the electronic storage componentry, and for conditionally generating a control signal based on the initial probe usage time.
By way of non-limiting example, the control unit is an RF generator with a microprocessor as the control circuit. The microprocessor is configured for determining an elapsed probe usage time based on the initial probe usage time and a reference time derived from the timing signal. The elapsed probe usage time is compared with a predetermined elapsed time limit, which may be read from the electronic storage componentry, or alternatively obtained from another source. This comparison may be performed only once after connection of the medical probe to the RF generator, or alternatively, periodically after connection of the medical probe to the RF generator. The RF generator conditionally generates an interlock control signal based on this comparison. The RF generator includes an interlock device coupled to the microprocessor, which prevents operation of the medical probe in response to the interlock control signal by preventing an RF power source from outputting power.
In another preferred embodiment constructed in accordance with still a further aspect of the invention, a medical probe includes an elongate member carrying electronic storage componentry having a predetermined elapsed time limit stored therein. By way of non-limiting example, in the preferred embodiment, the electronic storage componentry is a non-volatile storage component, such as, e.g., an EEPROM. Alternatively, the non-volatile storage componentry can comprise other components in which data can be written on-the-fly. For example, the non-volatile component can comprise Flash Memory, battery backed static RAM, a super-capacitor discharging into a resistor, an electrolytic elapsed time indicator, etc.
Other and further objects, features, aspects, and advantages of the present invention will become better understood with the following detailed description of the accompanying drawings